The mere fact that the worst relief pitcher in politics was called in to try to strike out Donald Trump in the bottom of the ninth shows you how weak the Republican bench is these days.

There is no stopping Trump. Not on the field — where Mitt Romney, whom Trump accurately labeled “a stiff,” was laughed off the mound — or in the locker room, where Ted Cruz and Marco Rubio have helped turn the GOP debates into a snapping towel contest, “big hands” jokes and all.

At this point, the Republican establishment appears to have two choices, both bad. Swallow hard and go with Trump, or somehow deny him the nomination at the convention.

Both roads end at the cliff. The first brings likely disaster for Republican candidates from the Senate to the mosquito abatement board, and Hillary Clinton ends up president. The second probably results in Donald Trump running as an independent, and Hillary Clinton ends up president.

Under Option One, there might be a Republican Party left when it’s all over. Under Option Two, probably not.

Meanwhile, voters are having a ball. They haven’t been this entertained in years. Lincoln-Douglas has given way to Beavis and Butt-head.

More by Willie Brown

San Francisco District Attorney George Gascón made a rookie political mistake when he created his blue-ribbon task force of three retired judges to look into allegations of racism and homophobia within the Police Department. Now it has come back to bite him in the backside.

Seeing as how Gascón used to be police chief, he should have handed the task of pulling the department’s skeletons out of the closet to a neighboring D.A., like San Mateo County’s Steve Wagstaffe or Alameda County’s Nancy O’Malley. Then he should have stepped as far away as possible.

Instead, Gascón has put himself in the position of taking on the Police Officers Association.

Gascón has been privately calling the allegation pure BS, but he has yet to say so in public — choosing instead to have his office’s spokesman issue a non-denial denial that accused Delagnes of lacking credibility.

Delagnes is holding back on specifics, saying he’ll lay it all out if the blue-ribbon panel asks him to testify. If it does, it will be a circus. If it doesn’t, Delagnes and the police union will cry coverup.

Either way, the union has put Gascón in a box of his own making.

I can’t remember the last time I’ve seen so many well-dressed former federal agents and retired cops as I did during the big corporate cybersecurity confab at Moscone Center last week.

They filled the bars and restaurants to the brim. All of them having a ball. And all of them on expense accounts, no doubt.

And talk about being supersensitive.

Wednesday evening, right around rush hour, one of the snoop busters left a “suspicious package” at the corner of Third and Howard.

The next thing you know, the place was swarming with cops, the yellow tape was going up and the surrounding hotels going on lockdown.

Everyone stood in the lobbies, gazing out as the tanklike bomb squad van rolled up to face the terror threat.

It was like they were shooting a movie.

In this case, a comedy. The “bomb” turned out to be a conventioneer’s backpack.

Real movie time: “Triple 9.” Woody Harrelson and Kate Winslet are the two big names in his cop double-cross caper, which will have you talking for a good hour after you leave the theater. But even then, chances are you still won’t have figured out half the plot twists. If you do, give me a call.

The San Francisco State Guardian Scholars program and John Burton held a joint fundraiser the other night to help foster kids over 18 with their college education. It was an impressive affair.

The graduation rate for students in the S.F. State program is 75 percent. The graduation rate for foster kids left on their own is 3 percent. Now that is what I call making a difference.

The revelation that a knife had turned up that might be linked to the O.J. Simpson case took me back to the the day the verdict came down in his double-murder trial.

I had just flown into Seattle. My brother James greeted me at the gate and said there were some local reporters who wanted my comment on the verdict.

“What was it?” I asked.

“The Los Angeles district attorney tried to frame a guilty man and failed.”